Sawing method for a wafer

ABSTRACT

The present invention relates to a sawing method for a wafer. The sawing method of the invention comprises: (a) providing a wafer, the wafer having an active surface and a back surface, the active surface having a plurality of sawing lines; (b) coating a protection layer on the active surface and the sawing lines; (c) taping a grinding tape on a surface of the protection layer; (d) grinding the back surface of the wafer to thin the wafer; (e) removing the grinding tape; and (f) sawing the wafer to form a plurality of dice. Whereby, the problems of die cracking, die scratching, die contamination and peeling of the surface of the sawing lines can be avoided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a sawing method for a wafer, particularly to a sawing method for a wafer with a protection layer coating on a surface of the wafer.

2. Description of the Related Art

FIGS. 1 to 4 show the steps for a conventional sawing method. Referring to FIG. 1, firstly, a wafer 10 is provided. The wafer 10 has an active surface 101 and a back surface 102, and the active surface 101 has a plurality of sawing lines (not shown). A grinding tape 11 is then taped on the active surface 101. The grinding tape 11 is used to protect the active surface 101 in the following grinding process.

Referring to FIG. 2, the wafer 10 is thinned by grinding the back surface 102. For the conventional sawing method, the wafer 10 is thinned by using the grinding wheel of a grinding machine (not shown) to grind the back surface 102. The grinding tape 11 is then removed, as shown in FIG. 3. Finally, the wafer 10 is sawed by using cutting tools along the sawing lines on the active surface 101 to form a plurality of dice 12, as shown in FIG. 4.

According to the conventional sawing method, there is no protection layer to protect the wafer 10 after the step of thinning the wafer 10, so that the surfaces of the sawing lines peel when sawing the wafer 10. Furthermore, a larger area near the sawing lines may also peel, and the active surface 101 of the wafer 10 will be damaged and scratched. In addition, after the grinding step, the grinding tape 11 must be removed, and the wafer 10 is then sawed. Therefore, when sawing the wafer to form a plurality of dice, the active surface of the dice will be contaminated.

Consequently, there is an existing need for providing a sawing method for a wafer to solve the above-mentioned problems.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a sawing method for a wafer. The sawing method of the invention comprises: (a) providing a wafer, the wafer having an active surface and a back surface, the active surface having a plurality of sawing lines; (b) coating a protection layer on the active surface and the sawing lines; (c) taping a grinding tape on a surface of the protection layer; (d) grinding the back surface of the wafer to thin the wafer; (e) removing the grinding tape; and (f) sawing the wafer to form a plurality of dice.

According to the sawing method of the invention, the protection layer still attaches to the wafer after the step of thinning the wafer, so that the protection layer can provide protection for the wafer. Therefore, the surfaces of the sawing lines will not peel when sawing the wafer. Also, a larger peeling area near the sawing lines can be avoided, and the active surface of the wafer is not damaged and scratched. Furthermore, the protection layer is removed after the wafer is sawed, so that the active surface of the dice will not be contaminated when sawing the wafer to form the dice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the step for taping a grinding tape on a wafer according to a conventional method;

FIG. 2 shows the step for grinding the wafer according to the conventional method;

FIG. 3 shows the step for removing the grinding tape according to the conventional method;

FIG. 4 shows the step for sawing the wafer according to the conventional method;

FIG. 5 shows a wafer of the present invention;

FIG. 6 shows the step for coating a protection layer on the wafer according to the present invention;

FIG. 7 shows the step for taping a grinding tape on the wafer according to the present invention;

FIG. 8 shows the step for grinding the wafer according to the present invention;

FIG. 9 shows the step for removing the grinding tape according to the present invention;

FIG. 10 shows the step for sawing the wafer according to the present invention; and

FIG. 11 shows the step for removing the protection layer according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 5 to 10 show a sawing method for a wafer according to the present invention. Referring to FIG. 5, firstly, a wafer 20 is provided. The wafer 20 has an active surface 201 and a back surface 202, and the active surface 201 has a plurality of sawing lines (not shown). Referring to FIG. 6, a protection layer 21 is coated on the active surface 201 and the sawing lines, and the protection layer 21 totally covers the active surface 201 and the sawing lines. In the embodiment, the protection layer 21 is coated on the active surface 201 and the sawing lines by using a spin-coating method. The protection layer 21 is an adhesive. In the embodiment, the adhesive is epoxy.

After the step of coating the protection layer 21 on the active surface 201 and on the sawing lines, a baking step for solidifying the protection layer 21 proceeds so as to protect the wafer 20. Since the protection layer 21 coated on the active surface 201 is liquid material, the protection layer 21 can totally cover the active surface 201 and the sawing lines. Furthermore, by utilizing the liquid characteristics of the protection layer 21, the protection layer 21 can tightly attach to the active surface 201 and the sawing lines, and form with a very flat surface.

Referring to FIG. 7, a grinding tape 22 is taped on a surface of the protection layer 21. The grinding tape 22 can provide more protection for the wafer 20. Referring to FIG. 8, the wafer 20 is thinned by using the grinding wheel of a grinding machine (not shown) to grind the back surface 202. When the wafer 20 is ground, the tightly attached protection layer 21 and the grinding tape 22 can provide a supporting force for the edge of the wafer 20. Therefore, the problems of die cracking can be avoided, and the active surface 201 of the wafer 20 will not be damaged. Referring to FIG. 9, the grinding tape 22 is removed. The wafer 20 is then sawed by using cutting tools along the sawing lines on the active surface 201 to form a plurality of dice 23, as shown in FIG. 10. Finally, after the step of sawing the wafer 20, the protection layer 21 may further be removed by using a solvent, as shown in FIG. 11.

According to the sawing method of the invention, the protection layer 21 still attaches to the wafer 20 after the step of thinning the wafer 20, so that the protection layer 21 can provide protection for the wafer 20. Therefore, the surfaces of the sawing lines will not peel when sawing the wafer 20. Also, a larger peeling area near the sawing lines can be avoided, and the active surface 201 of the wafer 20 is not damaged and scratched. Furthermore, the protection layer 21 is removed after the wafer 20 is sawed, so that the active surface 201 of the dice 23 will not be contaminated when sawing the wafer 20 to form the dice 23.

While the embodiment of the present invention has been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention may not be limited to the particular forms as illustrated, and that all modifications that maintain the spirit and scope of the present invention are within the scope as defined in the appended claims. 

1. A sawing method for a wafer, comprising the following steps of: (a) providing a wafer, the wafer having an active surface and a back surface, the active surface having a plurality of sawing lines; (b) coating a protection layer on the active surface and the sawing lines; (c) taping a grinding tape on a surface of the protection layer; (d) grinding the back surface of the wafer to thin the wafer; (e) removing the grinding tape; and (f) sawing the wafer to form a plurality of dice.
 2. The sawing method according to claim 1, wherein the protection layer is coated on the active surface of the wafer by using a spin-coating method in step (b).
 3. The sawing method according to claim 1, wherein the protection layer is an adhesive.
 4. The sawing method according to claim 3, wherein the adhesive is epoxy.
 5. The sawing method according to claim 1, further comprising a baking step for solidifying the protection layer after step (b).
 6. The sawing method according to claim 1, further comprising a step for removing the protection layer after step (f).
 7. The sawing method according to claim 6, wherein the protection layer is removed by using a solvent. 